As shown in FIG. 1A, a fuel cell is generally composed of a bipolar plate 100 with a membrane electrode assembly 102 in between. The bipolar plate 100 is generally made of a graphite material or a metallic material, and the bipolar plate 100 may have a plurality of flow channels 100a after mechanical processing (including milling, punching, stamping, . . . etc.) or chemical processing (including etching, electroplating . . . etc.). The flow channels 100a are used for fuel (e.g., hydrogen and oxygen) transportation. Hence, the length, the sectional shape, and the size of the flow channels 100a may affect electrochemical reaction in the membrane electrode assembly 102, and further affects the overall electricity generation efficiency of the fuel cell. In addition to the flow channels 100a, the majority of the bipolar plate 100 further includes a plurality of ribs 104. The ribs 104 are used for supporting the membrane electrode assembly 102, and transferring electrons during the electrochemical reaction of the fuel cell.
FIG. 1B merely illustrates a portion where the rib 104 depicted in FIG. 1A is in contact with the membrane electrode assembly 102, wherein the membrane electrode assembly 102 includes a gas diffusion layer (GDL) 106, a catalyst 108, and a membrane 110. Since the rib 104 is generally made of a graphite material or a metallic material, the fuel may not be able to pass through the ribs 104; thus, the fuel may diffuse only within areas 112. In this case, the catalyst 108 within the overlap between the rib 104 and thereof may be lack of fuel; thereby, the electrochemical reactions of the catalyst 108 may be blocked, the effective utilization of the catalyst 108 may be decrease, and the material of the fuel-lacking area may be degraded.